Among the medical catheters commonly used to access vascular and other locations within the body and to perform various functions at those locations are those adapted to deliver and deploy medical devices such as stents, vascular filters, sensors and pacing devices to selected targeted sites in the body. Such medical devices typically are releasably carried at the distal region of the delivery catheter in a state ready to be deployed by the catheter after the distal end of the catheter has been navigated to and positioned at the target deployment site. In many cases, such as those involving cardiovascular vessels, the path to the deployment site may be tortuous and may present conflicting design considerations requiring compromises between dimensions, flexibilities, material selection, operational controls and the like. One such example is presented in connection with accessing the pulmonary artery through the right side of the heart that includes a path from access through the femoral vein, a path that requires multiple 180 degree bends.
Typically the advancement of the catheter within the patient is monitored fluoroscopically to enable the clinician to manipulate the catheter to steer and guide its distal end through the patient's vessels to the target site. In one common technique, a steerable guide wire is used to access the target site with the catheter being advanced over the guidewire to locate the distal end of the catheter at the target site. Other catheters have been designed to omit the guide wire and, instead, rely on a catheter construction in which the catheter itself may be steerable by providing one or more pull wires through the catheter by which the distal region of the catheter can be bent or deflected. By bending the distal end of the catheter and constructing the catheter to transmit controllably rotational movement from the proximal end to the distal end, the clinician may controllably steer the end of the catheter through bends in the vasculature. As with the wire-guided devices, when the distal end of the catheter is positioned at the deployment site, the catheter is operated to deploy the device
Although it is desirable, in many instances, to use a catheter with a small diameter to facilitate navigation through tortuous vasculature, small diameter catheters present various design difficulties resulting from competing considerations, resulting in design trade-offs. In general, incorporating more functions into a catheter will tend to result in a larger diameter catheter in order to contain the components required for the functions. For example, a wire-guided catheter may require a lumen in the catheter to contain the guide wire. If one or more wires is required to operate the deployment mechanism, that may require additional space within the catheter. In catheters that omit guide wires and, instead, are themselves steerable, the typical pull wire(s) and the connection to the catheter body may add to the size of the catheter as well as complexities in construction of the catheter.
It would be desirable to provide a delivery catheter for medical devices that embodies a simple construction and in which the number of components for navigating the catheter and deploying the medical device is minimized. It is among the objects of the invention to provide such delivery catheters and methods for deploying medical devices.